Stabilizer for well casing perforator



Dec. 1, 1959 R. B. HAMILL STABILIZER FOR WELL CASING PERFORATOR FiledMarch v 29, 1956 1/ I I z 1114; 11115;!

I. ri id-an Emma INVENTOR. Ruben B. Hamill, BY 5 ATTORNEY United StatesPatent F STABILIZER FOR WELL CASING PERFORATOR Robert B. Hamill, GreatBend, Kans., assignor, by mesne assignments, to Welex, Inc., acorporation of Delaware Application March 29, 1956, Serial No. 574,680

7 Claims. (Cl. 102-21.8)

. This invention generally relates to apparatus for perforating wellcasing by means employing the Munroe effect of shaped explosive chargesand more particularly relates to apparatus which will retain the mainbody of such apparatus in firing position during and immediately afterdetonating such charges.

Jet guns employing shaped charges are well developed and extensivelyused. Therefore, such guns need not be herein described in detail.Reference may be had to Patent No. 2,494,256 to Muskat et al. forembodiments of such guns with which the apparatus of this inventionmaybe advantageously used.

In use such guns are lowered into a well bore to a level of theformation which is to be produced and then fired by electrical ormechanical means. Upon firing, all the charges detonate at substantiallythe same instant. The firing of such charges creates considerable recoilwhich usually causes the gun to buck or bounce upwardly in the wellbore. This bucking does not affect the perforating efficiency of thegun, but can be detrimental to the cable from which the gun issuspended. On occasion the travel upward and the subsequent drop of thegun has been sufliciently pronounced to seriously kink, knot, or partthe cable. The usual effort to circumvent this problem has been toincrease the mass of the gun proper or to attach weights to the gun.Such efforts have proved helpful, but require stronger cable to supportsuch apparatus. For long sections of. guns' having large numbers ofcharges the necessary extra strength can require excessively expensivehoisting cable.

It is, therefore, the general objects of this invention to provide anapparatus with which the gun may be steadily supported after firing,which will be relatively light and easily handled, and which may be usedrepeatedly without manual resetting.

' Briefly described, the stabilizer comprises a body adapted to beattached to a jet perforator and in pressurable communication with thechamber containing the explosive charges. Adapted to engage said body insupporting contact with a Well casing wall are one or more pressureactuated slip wicker members. Hydraulic pressure transmitting meansincluding provision for substan tially instantaneous fluid transferfrom. said chamber to said wickers and minute transfer for fluidsreturning from said wickers to said chamber is provided intermediatesaid chamber and said wickers. The arrangement is such that a pressurecreated in said chamber immediately expands and sets said wickers, andthen, as the pressure diminishes, said wickers gradually release andretract to their original position, thus allowing the gun to be removedfrom the well bore.

The invention may be more fully understood by refer-' ence to theaccompanying drawing in which:

Figure 1 illustrates a cross section of a cased well bore in which theinvention, in combination with a jet perforating gun, is positioned.

2,915,011 Patented Dec. 1, 1959 Figure 3 is a cross sectional elevationof the invention in the expanded position.

Now referring to Figure 1, a jet perforating gun It) is shown inposition for firing in a cased and normally liquid filledwell bore 12.For clarity a portion of the gun 10 is shown in cross section.Illustrated in this section is one of the shaped charges 14 which has aprimacord detonating means 16 threaded therethrough in common with theremaining charges. The upper end of this cord 16 is attached to anelectrical or percussion type blasting cap which may be detonated atwill. Also shown in this cross section is the interior chamber 18 of thegun. Prior to firing this chamber is isolated from and free of wellfluids.

In referring to Figures 2 and 3, it is seen that the lower end ofchamber 18 is in pressurable communication with the upper portion of astabilizer 20 provided by this invention. Forming this stabilizer 20 isa generally cylindrical body 22 having a blind bore 24 therein whichterminates near the lower end of said body. Radially disposed about theaxis of body 22 are one or more slip wickers 26. Said wickers aremounted in the body 22 in closely fitted fashion and backed by resilientpressure pads 28. Pressure communication is provided from the undersideof pads 28 to bore 24. The arrangement is such that pressure appliedunder said pads will force said wickers to extend out into contact withthe casing wall. Retainer springs 30 are provided to normally supportwickers 26 in a retracted position and to forceably retract said wickersfrom such an extended position.

Located within the bore 24 and immediately above the passages providedto pads 28 is a one way flow means, for example, a spring loaded ballcheck valve 32. As provided, the valve 32 readily allows fluid passageinto that portion of the bore 24, thereinafter called 24A, communicatingwith the wickers 28, but prevents fluid return therefrom.

Provided adjacent to the seat of check valve 32, in such manner as toshunt return flow past the valve, is a restrictive passage 34. Thispassage allows only a minute 7 flow therethrough and provides the solereturn of fluids in the normally retracted position.

trapped by check valve 32.

Forming a chamber in bore 24 and above valve 32 is a pressure responsivemember, exampled by a spring loaded piston 36, which is retained in saidbore by a retaining ring 38. Escape of fluids past piston 36 isprevented by sealing means, exampled by an O ring 40.

That entire chamber formed by bores 24 and 24A, the passages to pads 28,and piston 36 is completely filled with some incompressible hydraulicfluid, such as oil.

In operation the stabilizer 20 is attached to the gun 10 in the positionillustrated in Figures 1 and 2. The gun 10 is then lowered to a desireddepth and fired. The detonation of the charges 14 blast away theirretaining caps and perforate through the casing and into the wellformation. This detonation also creates a tremendous initial pressurewithin chamber 18 which may be several times greater than thehydrostatic pressure caused about gun 10 by the well bore liquids. Thisdetonation pressure soon subsides through the now open perforating 3,the wickers 26 are expanded thereby into extremely forceful contact withthe well casing wall, and thus effectively prevent movement of gun 10.It has been found that the relative inertia of gun 10 to that of theinternal components of stabilizer 20 is such that the' wickers 26areexpanded and set into supporting contact with the well casing Wallbefore any appreciable move ment of the gun has occurred.

As the pressure gradually subsides from chamber 18 the fluid trapped inchamber 24A by check valve 32 remainsat the initial detonating' pressureand thus seeks the subsiding pressure level found in the chamber 24through restriction 34. A minute fluid flow then commences from chamber24A through restriction 34 to chamber 24, gradually relieving thepressure under the pads 28. The spring loading of piston 36, aided bythe hydraulic fluid returning to chamber 24, returns the piston to itsinitial position, as illustrated in Figure 2. As the hydraulic fluidleaves chamber 24A, the pressure across pads 28 becomes equal. Thewickers 26 thereon lose forceful contact with the well bore walls andare forced to retract, in response to the springs 30, into the positionalso illustrated in Figure 2. The gun may now be withdrawn from the wellfor reloading and reuse. It is pointed out that Figure 3 illustrates thecheck valve 32 while fluid is being forced into chamber 24A. It is seenthat the valve will immediately close when the full pressure has beenapplied and becomes equal in chambers 24 and 24A.

It is to be noted that the stabilizer is readied for repeated use in anautomatic fashion and requires no manual resetting. Also to be noted isthat any mud or detritus entering the chamber 18 through the openperforating ports of the gun 10 is effectively isolated from theinterior of the stabilizer 20 by means of piston 36.

While various changes and modificationsmay be made in the embodiment ofthe invention disclosed herein, all such changes which will fall withinthe scope of the appended claims are intended to be embraced thereby.

That which is claimed is:

l. A device for perforating casing in well bores, comprizing, a jetperforating gun having shaped explosive charges positioned in a fluidtight chamber in said gun, a hollow cylindrical body connected to saidgun in pressurable communication with said gun chamber at one end ofsaid body, said body being closed at the other end, one or moreretractable wicker members radially disposed about said body andradially movable in response to pressure applied from within said body,hydraulic means in said body to provide pressure communication from saidgun chamber to said wickers, and a flow control means disposed in saidbody intermediate said gun chamber and said wickers including means toprovide an immediate pressure transfer through said hydraulic means fromsaid gun chamber to said wickers and means to provide a retardedpressure transfer through said hydraulic means from said wickers to saidgun chamber.

2. In combination with a jet perforating gun having shaped explosivecharges positioned in a fluid tight chamber in said gun, a stabilizerbody connected to said gun in pressurable communication with saidchamber, said body comprizing, one or more retractable wicker memberstherein movable to engage a well bore casing in response to pressureapplied from within said body, and hydraulic means intermediate saidwickers and said chamber for transmitting pressure from said chamber tosaid wickers, said hydraulic means having means therein for providinglarge flow from said chamber to said wickers and providing a minutereturn flow from said wickers to said chamber.

3. In a jet perforator for use in oil wells or the like, the combinationof a gun body having a chamber therein, shaped explosive charges mountedin said body in such manner as to create, upon ignition, an initialpressure in said chamber in addition to the creation of the perforatingjet, pressure responsive wickers mounted on said body being adapted toanchor said body to the casing in the well during the detonation of saidcharges, and hydraulic means in connection with said chamber and saidwickers being adapted to cause said wickers to immediately grip saidcasing in response to the initial pressure created in said chamber uponthe ignition of said charges and to release said casing following thedetonation of said charges.

4. Well casing perforating apparatus including, a jet perforating gunhaving an explosive charge chamber therein, a stabilizer body having achamber therein, means for connecting said body to said gun in pressuretransferring relation of said body chamber to said gun chamber, apressure actuated extendable and retractable retaining means including awicker member disposed in said body in pressure transferring relationwith said body chamber for extending into retaining engagement with awell casing upon application of a differential pressure applied fromwithin said gun chamber to within said body chamber and retracting fromsaid casing upon removal of said pressure, hydraulic pressure transfermeans disposed within said body chamber for transferring differentialpressure from said gun chamber to said retaining means, and pressurecontrol means disposed within said body chamber intermediate saidretaining means and said connecting means including means for providingimmediate transfer of fluid pressure to said retaining means and meansfor providing extremely retarded fluid pressure transfer from saidretaining means.

5. In jet perforating apparatus the combination ineluding, a jetperforating gun having an explosive charge chamber therein, a stabilizerbody having a chamber therein, means for connecting said body chamber inpressure transferring relation to said gun chamber, at least one fluidpressure actuated wicker member disposed in extendable and retractablerelation within said body for forceably engaging a well casing inresponse to fluid pressure applied from said gun chamber to within saidbody and retracting from said casing upon removal of said pressure,hydraulic pressure transfer means disposed in said body intermediatesaid wicker member and said connecting means for transferring fluidpressure to said wicker member, and flow control means for controllingsaid hydraulic means including means for providing immediate flowtransfer of said hydraulic means to transfer pressure to said Wickermember and means for providing extremely slow return flow transfer ofsaid hydraulic means for pressure transfer from said wicker member.

6. Jet perforating apparatus comprising, a jet perforating gun having anexplosive charge chamber therein, a body having a chamber therein, meansfor connecting said body chamber in pressure transferring relation tosaid gun chamber, a pressure actuated extendable and retractableretaining means including a Wicker member disposed in said body inpressure transferring relation with said connecting means for extendinginto retaining engagement with a well casing upon application of adifferential pressure applied from said gun chamber to within said bodyand retracting from said casing upon removal of said pressure, hydraulicfluid disposed within said body chamber, and fluid pressure controlmeans disposed within said body chamber intermediate said retainingmeans and said connecting means for controlling the passage of saidhydraulic fluid including means for providing immediate transfer ofhydraulic fluid pressure to said retaining means and means for providingextremely retarded hydraulic fluid pressure transfer from said retainingmeans.

7. Apparatus as described comprising, a jet perforating gun having anexplosive charge chamber therein, a body having a chamber therein, meansfor connecting said body chamber in pressure transferring relation tosaid gun chamber, at least one fluid pressure actuated Wicker memberdisposed in extendable and retractable relation within said body forextending into forceable engagement with a well casing in response tofluid pressure applied from said gun chamber to within said body andretracting to said body upon removal of said pres- References Cited inthe file of this patent UNITED STATES PATENTS Nixon et al. Jan. 2, 1934Witt Mar. 4, 1941 Baker Mar. 8, 1955 Kanady Apr. 12, 1955

